Roentgenium (Rg)

Roentgenium is a chemical element with symbol Rg and atomic number 111. It is named after physicist Wilhelm Röntgen. As a synthetic element, it can be created in a laboratory but is not found in nature.

Atomic Number

111

Atomic Mass

282 u

Phase

Predicted solid

Density

~28.7 (predicted) g/cm³

Electron Shells

2, 8, 18, 32, 32, 17, 2

Atomic Structure

Protons: 111 • Electrons: 111 • Neutrons: Varies by isotope

Electron Configuration: 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁶ 5s² 4d¹⁰ 5p⁶ 6s² 4f¹⁴ 5d¹⁰ 6p⁶ 7s² 5f¹⁴ 6d⁹

Discovery

1994 • Sigurd Hofmann, Gottfried Munzenberg